With the continuous development of semiconductor technology, semiconductor devices have been more and more widely used, and the requirements on the performance of semiconductor devices have also become higher and higher.
Transistor with a metal-oxide-semiconductor (MOS) structure is known as a MOS transistor. As a basic semiconductor device, the MOS transistor demonstrates many advantages such as simple drive circuit, small required drive power, fast switch speed, and high operation frequency. Therefore, the MOS transistor has been widely used as switch devices in various circuits, including radio-frequency (RF) circuits, etc.
In the field of electronic technology, the characteristics of RF circuits are different from the characteristics of the conventional low-frequency circuits. This is mainly because that the circuit characteristics under high frequency conditions are different from the circuit characteristics under low frequency conditions. Specifically, under high frequency conditions, stray capacitance and stray inductance have significant impact on the circuits.
Stray inductance in a semiconductor device includes inductance at the wire connections and internal self-inductance of the components. Stray capacitance in a semiconductor device includes capacitance between the conductors of the circuits and also between the components and the ground. For example, the overlapping capacitance between the gate electrode and the source/drain extension region is in the stray capacitance category. Further, the on resistance of RF circuits may have important influence on the energy consumption of the RF circuits, and thus may affect the signal strength of the RF circuits.
However, MOS switches formed by conventional methods have several disadvantages such as large on resistance (RON), large overlapping capacitance (COV), etc., and such disadvantages may result in large switch signal loss and lead to undesired performance of the MOS switches. The disclosed semiconductor devices and fabrication methods thereof are directed to solve one or more problems set forth above and other problems in the art.